22 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



We know about 100 chemical elements, but the physical 

 substance of organisms is composed almost entirely of 

 about half a dozen of these elementary substances. Does 

 not all this mean that the vital tendency finds resistance 

 from matter? It is impossible that all that it implies can 

 be manifested in one material aggregation; and in 

 the face of this resistance, this inability to influence 

 completely energetic happening, the vital impetus has 

 undergone dissociation. 



Evolution has consisted therefore in the splitting up 

 of the multiple bundle of tendencies which we call the 

 vital impetus. Obviously the main cleavage consisted 

 of the separation of plant and animal modes of meta- 

 bolism. We have only indications of the possibility of 

 the co-existences of these in the same organism, and 

 everything points to the conclusion that in the physical 

 conditions characterising our earth the accumulation of 

 energy was incompatible with its expenditure. After 

 this scission animal life became directly dependent on 

 that of the plant. Numerous other main cleavages 

 occurred on both the plant and animal sides, and we are 

 not directly concerned here with the nature of these 

 splittings. We think of them, in a way, as determined 

 mechanically, each of them an experiment with the 

 object of getting the better of inert matter, and most of 

 them unsuccessful experiments. Judging success by the 

 widest possible distribution over the earth, and the power 

 of living amid the most diverse conditions, we see that 

 three great groups of organisms have become dominant 

 ones : the green plants ; the arthropods culminating 

 in the Hymenoptera and ants ; and the vertebrates 

 culminating in man. 



In this latter cleavage we see the separation of two 

 modes of acting — instinct and intelligence. Without 



